Proceedings Am. Philos. Soc. Vol. LI. No. 204 



Plate III 



4 



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Frightened rabbit : Cerebellum. The rabbit was frightened once and killed iniiiit- 

 diati'lv. The average of ten differential Purkinje cell counts from ten such experiments 

 was : Active cells, 83.4 per cent.; fatigued cells 15.7 per cent.; exhausted cells, 0.9 per 

 cent. 



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Frightened rabbit: Cerebellum. The rabbit was frightened once and killed at the 

 end of two and one half hours. The average of five difi'erential Purkinje cell counts from 

 five such experiments was: Active cells, 55.6 per cent.; fatigued cells, 35-4 per cent.; 

 exhausted cells, 9.0 per cent. 



Fear in Rabbits. 



These cuts and the cell counts as given above illustrate several important points, viz., 

 that cerebral stimulation by fear causes, first, demonstrable morphologic changes in brain 

 cells, second, a marked early increase in the number of active [and hence also hyper- 

 chromatic] cells, and, third, that this stimulation is followed by later and more serious 

 morphologic changes in the cells which do not attain a maximum until from 2j^^ to 6 

 hours have elapsed after the period of fright. 



